The cleaning of narrow internal channels of flexible endoscopes with liquids at low flow velocities is inadequate because of a fundamental limitation of fluid dynamics. To achieve efficient cleaning, sufficient turbulence and high shear stresses must be applied to the channel surface. The turbulent two-phase flow method invented by Novaflux satisfies these conditions for channels with different diameters. In Phase I, an automated-programmable device was designed and constructed to deliver two-phase flow to the "entire" surface of internal-channel system using a new flow paths circuit. 6 to 8 log 10 reduction of Bacillus subtilis spores from internal channels were consistently achieved with the two-phase method. The efficiency of cleaning was independently verified with the radionuclide method using Tc99. Rivulet and dispersed flow patterns were found to predominate the cleaning of air-water channel at velocities> 30 m/s. The two-phase cleaning appears to occur by erosion of soil by droplet impact (high shear stresses) and by "efficient" rinsing to remove soil fragments produced during cleaning. The Specific Aims of the Phase II are: 1) To design, construct and test a revised and complete endoscope-reprocessing device to perform a validated cleaning and disinfecting protocol based on the turbulent two-phase cleaning technology. 2) To validate internal channel cleaning with the two-phase method using predictive evaluation methods including: radionuclide and visual inspection, and microbial recovery methods. 3) To study and validate the cleaning parameters for internal channels of flexible endoscopes. 4) To study and validate a disinfecting cycle to achieve high-level disinfection (HLD) or possibly sterilization in conjunction with the two-phase cleaning process. 5) To conduct comprehensive in-vitro simulation studies mimicking patient soil and diverse microorganisms to validate a protocol to be used in the clinical studies. 6) To conduct multi-center clinical studies to evaluate and validate the reprocessing method and device for endoscopes made by different manufacturers. PROPOSED COMMERCIAL APPLICATION: More than 10 million gastrointestinal endoscopic procedures are performed each year in the United States with the number growing at a rate of 7.5% per year. The most significant problem with current commercial automated endoscope reprocessors (AERs) is their inability to remove soil and organisms from internal channels since such reprocessing devices are not designed to perform a validated cleaning cycle. In addition, glutaraldehyde is a known carcinogen to which many people have strong allergic reactions. The alternative liquid germicide is peracetic acid as used by Steris; it is also corrosive and results in damage to endoscope components. Commercial AERs sell in the range of $10,000 to $30,000 depending on their capacity to simultaneously reprocess more than one endoscope at a time and on other technology features such as automatic record keeping systems. A device capable of processing only one endoscope at a time now sells in the $10,000 range. These devices have lifetimes in the five to seven years range. Total domestic yearly sales are estimated to be approximately the equivalent of 2500 single endoscope capacity units per year with an additional 5000 units sold abroad. Thus the annual worldwide market is in the 150 million dollars range. Other revenues are derived from ancillary equipment sales, parts replacement, training sessions and maintenance contracts. Novaflux believes that it can rapidly capture revenues by licensing the technology to existing market leaders or by offering a new product. The benefits to the health care industry derived from using the technology are: 1. Reduced risk of patient infection from endoscopy procedures: Treatment of nosocomial infections in 1.4 million hospital patients is estimated to have cost nearly $6.5 billion last year. Although the official cited risk of infection is low for endoscopy procedures, most experts concede the majority of infections go undetected or result in non-life threatening reactions. 2. Shorter reprocessing time and reduced labor costs: Most endoscope reprocessing protocols currently require between 30 to 60 minutes of time with a part of it consisting of manual cleaning. Substituting most of the cleaning cycle by the automated Novaflux device would save between 10 and 15 minutes per processing and would thus offer a significant savings in staff labor. According to recent estimates, labor accounts for 44% of total cost of an endoscope cleaning and disinfection procedure and the cited cost per cleaning was in the $30 range. Thus labor savings of approximately $4 per procedure or up to 40 million dollars would be saved annually in the US. 3. Reduced maintenance costs and longer equipment lifetime: Endoscope maintenance is also a major factor in the overall cost of reprocessing. The Shields study infers that maintenance concerns result in the need for a large inventory of endoscopes to counter the effects of reprocessing on procedure scheduling. A recent survey by Urayama et al. indicates that the average lifetime of an endoscope is between 4.6 and 6.9 years depending on the type of instrument. Given instrument costs as high as $30,000 a reprocessing procedure that minimizes damage to the instrument and possible equipment service life extension offers a significant cost benefit to the health care provider. In summary the promise of these benefits should offer a significant incentive to the adoption of the two-phase cleaning technology in endoscope reprocessing.